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https://github.com/grrowl/react-keyed-flatten-children
Flattens React children and fragments to an array with predictable and stable keys
https://github.com/grrowl/react-keyed-flatten-children
react typescript
Last synced: 7 days ago
JSON representation
Flattens React children and fragments to an array with predictable and stable keys
- Host: GitHub
- URL: https://github.com/grrowl/react-keyed-flatten-children
- Owner: grrowl
- License: mit
- Created: 2019-11-20T07:37:42.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2024-09-27T05:10:48.000Z (about 1 month ago)
- Last Synced: 2024-10-25T18:44:19.723Z (12 days ago)
- Topics: react, typescript
- Language: TypeScript
- Homepage: https://www.npmjs.com/package/react-keyed-flatten-children
- Size: 200 KB
- Stars: 136
- Watchers: 3
- Forks: 5
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# react-keyed-flatten-children
Similar to [React's built-in `Children.toArray` method](https://reactjs.org/docs/react-api.html#reactchildrentoarray), this utility takes children and returns them as an array for introspection or filtering. Different from `Children.toArray`, it will flatten arrays and `React.Fragment`s into a regular, one-dimensional array while ensuring element and fragment keys are preserved, unique, and stable between renders.
## getting started
```
npm install react-keyed-flatten-children
```
```
yarn add react-keyed-flatten-children
```
## why?
From the documentation of Children.toArray:
> [toArray] returns the children opaque data structure as a flat array with keys assigned to each child. Useful if you want to manipulate collections of children in your render methods, especially if you want to reorder or slice this.props.children before passing it down.
Unfortunately it has some thorny edges:
- [Children.toArray does not traverse into fragments](https://github.com/facebook/react/issues/6889), which limits flexibility of its use.
- Existing solutions exist, but they do not preserve the keys of the children and fragments, which throws away valuable performance optimisations provided through React keys.
- You're might be doing something a little wild, so you want the concept of "children" to as predictable as possible for you, and for the consumers of your library or component, [to avoid issues like this down the line](https://github.com/ReactTraining/react-router/issues/5785#issuecomment-351067856).
Some have proposed, soon after Fragments were introduced, that [a built-in `React.Children.toFlatArray` would be useful](https://github.com/reactjs/rfcs/pull/61), but it was decided against since "`React.Children` is in maintenance mode" until a better solution is devised.
[View the codesandbox here](https://codesandbox.io/s/react-keyed-flatten-children-example-yghsp) to get hands-on with how and when to utilise this module.
### for using this in your app
I've written a more application-focussed explanation in my article ["Addressing Children.toArray's thorny edges"](https://tommckenzie.dev/posts/react-keyed-flatten-children.html).
### for library authors
In most cases `react-keyed-flatten-children` is a drop-in replacement for `Children.toArray`.
```jsx
import flattenChildren from "react-keyed-flatten-children";
const MenuList = ({ children }) => {
const [selectedKey, setSelectedKey] = useState(null);
return (
{flattenChildren(props.children).map(child => {
if (child.type === MenuItem) {
return React.cloneElement(child, {
selected: child.key === selectedKey,
onClick: () => setSelectedKey(child.key)
});
}
return child;
})}
);
};
```
Now consumers can use arrays, fragments, or conditionally render items and your library will continue to work predictably.
```jsx
Animals
Dogs
Cats
Cars
{CARS_ARRAY.map(car => (
{car}
))}
{isLoggedIn() && (
<>
User
You!
Someone else!
>
)
```
### for everyone else
Work around libraries which don't support fragments passed into children.
```jsx
import flattenChildren from "react-keyed-flatten-children";
import { Switch, Route } from "react-router";
// A looks through its children , but won't match within fragments.
// will flatten out its children so is able to see all children.
const FlexibleSwitch = ({ children }) => (
{flattenChildren(children)}
);
const AppRoutes = ({ user }) => (
{user && (
<>
>
)}
);
```
## license
MIT